A prior art air brake system of this type is shown and disclosed in Japanese Pat. No. 45-6082.
Such a prior art air brake system is shown and will be explained hereinafter with reference to FIG. 2.
As shown in FIG. 2, a brake valve BV is conveniently located in the cab of the locomotive or lead railway car with easy reach of the motorman. The other parts or components of the system, such as, the electromagnetic direct connecting controller MSC, the electromagnetic brake valve BMV, the electromagnetic release valve RMV, the relay valve RV, the brake cylinder BC, and any other equipment are usually located underneath the floor of the railway car.
In viewing FIG. 2, it will be appreciated that the brake valve BV is in the release position and the brake cylinder BC is in an exhausted condition. In this release state, the control pipe or line CP is exhausted by the brake valve BV so that it is at atmospheric pressure. Thus, the movable linkage ML of the electromagnetic direct connecting controller MSC, which is connected to the diaphragms D4 and D5, is moved to the left by the bias return spring SP, as shown in FIG. 2. Accordingly, the release application contact point S1 is closed, while the brake application contact point S2 is opened.
Because the brake application contact point S2 is opened, the brake command line BS is disconnected from the power source E. Thus, the electromagnetic brake valve BMV deenergizes and its valve is seated and closed, so that the direct connecting line SAP is blocked off from the main air supply or reservoir line or pipe MRP. However, since the release application contact point S1 is closed, the release command line RS is connected to the power source E. Thus, the electromagnetic release valve RMV is energized and its valve is opened, so that the direct connecting line SAP is exhausted to atmospheric pressure.
Therefore, the air supply valve ASV of relay valve RV is closed, and also the hollow exhaust valve rod EVL moves downward, as viewed in FIG. 2, and exhausts the brake cylinder BC.
Now, when the brake valve BV is operated in brake application position, the control line CP is pressurized to an amount according to the selected brake operation position. Thus, the pressure on the left side of diaphragm D4 overcomes the biasing force of the return spring SP and moves the movable linkage ML to the right, as shown in FIG. 2. The movement of the movable linkage causes the release application contact point Sl to initially open, so that the release electromagnetic valve RMV is deenergized and its valve is seated and closed. This causes the direct connecting line SAP to become shut off to the atmosphere.
Next, as the movable linkage ML moves further to the right, the brake application contact point S2 will assume a closed position. The closing of point S2 causes the brake electromagnetic valve BMV to become energized and its valve is opened. Thus, air pressure is supplied from the original air reservoir line MRP to the direct connecting line SAP.
Since the direct connecting line SAP is now pressurized, the exhaust valve rod EVL of the relay valve RV moves upward and causes the air supply valve ASV to open. Thus, air pressure from the air reservoir AR is supplied to the brake cylinder BC to apply the brakes.
In addition, since the direct connecting line SAP is pressurized, the movable linkage ML is slightly moved back to the left. Now, when the respective forces on diaphragms D4 and D5 are balanced, the movable linkage causes the brake application contact point S2 to be opened. Because of this, the electromagnetic brake valve BMV is deenergized and its valve closes. Thus, no further pressurization of the direct connecting line SAP occurs. At this time, the release application contact point S1 is still opened. Therefore, the air pressure in the direct connecting line SAP remains the same at this time, while the relay valve RV also maintains pressure constant in the brake cylinder BC. This brake operating status is generally called a lap condition.
In this lap condition, the brake valve BV is operated to a low notch brake position from its release operation, so that the control line CP is pressurized according to the particular brake notch position. Thus, the movable linkage ML moves to the left so that the release application contact point S1 is closed and the electromagnetic release valve RMV is energized and its valve is opened, so that the direct connecting line SAP is exhausted. Since the direct connecting line SAP begins to exhaust, the movable linkage ML moves to the right so that the release application contact point S1 is opened. Thus, the electromagnetic release valve RMV is deenergized and its valve is closed, so that the exhausting of the direct connecting line SAP is stopped and it assumes a lap condition, as described above.
At this time, the relay valve RV is exhausted to a corresponding pressure with the direct connecting or straight air line SAP, so that the brake cylinder BC is also pressurized as a function of the brake position after the above-mentioned release operation.
Following this, the brake valve BV is operated to the release position, each structural component returns to the release state, as shown in FIG. 2.
As shown, in FIG. 2, a pressure regulating valve PRV and a check valve CHV are connectable to exhaust exit port EX via the brake valve BV.
The above-mentioned embodiment of a prior art system is constructed so that the pressure in the control line CP is pressurized or exhuasted by the brake valve BV at the motorman's cab, and the air brake apparatus underneath the car floor is operated in response to the pressure of this control line CP. Therefore, the brake line BP is connected to the control line CP which is connected to the electromagnetic direct connecting controller MSC, and the first air supply line P1 is connected to the main air reservoir line MRP while the second air supply line P2 is connected to the pressure regulating valve PRV, and the exhaust line P3 is open to the atmosphere.
However, it will be appreciated that it is necessary to provide sufficient space to pull the four lines or pipes CP, P1, P2, and P3 from underneath the car floor to the motorman's cab and, additionally, to couple these pipes to the brake valve BV in the motorman's cab.
In addition, the brake system of a modern car often uses the main controller which includes the brake controller having the brake command and release command outputs taking the form of electric signals. Thus, the driver or motorman experiences a different operational response or feeling with this electric command type controller than with the previous existing pneumatic type brake valve BV. Therefore, it used to be a burden for the driver who had to handle both the electrical controller and the brake valve BV in the different command systems.
In addition, since both of the command systems are fundamentally different, it is difficult to utilize the above-mentioned main controller in the electromagnetic direct connecting air brake system.